Sudden cardiac arrest remains a serious public health issue. Approximately 350,000 individuals are stricken in the U.S. annually, with overall survival rates on the order of only 5%. Even with the immediate availability of the most advanced care currently available, a survival rate of 25% appears to be the best-case scenario. Improved therapies to deal with this situation are clearly needed. Prior studies have shown that moderate hypothermia (approximately 3-5 C degrees) provided during and after cardiac arrest can reduce the level of damage to vital organs, including the brain. However, conventional noninvasive means that are available for cooling (such as water-filled cooling blankets and cool air-emitting coverings) are too slow for optimal treatment. Furthermore, they are not well suited to being used during administration of cardiopulmonary resuscitation (CPR). Life Recovery Systems (LRS) intends to develop an advanced, noninvasive Therapeutic Hypothermia Device (THD) for rapid and controlled reduction of core body temperature. To achieve this goal, this system will combine the use of components, which will provide highly efficient and regulated cooling of the skin. The THD will be designed in such a manner that it can be used in combination with advanced forms of CPR, so that cooling can be efficiently delivered even while the subject is in a state of cardiac arrest. Initial swine tests of a THD prototype have shown that it is capable of reducing body core temperature approximately twice as quickly as can be done by covering the animal with packed ice. The THD cooling rate was approximately fifty times greater than that reported in recent clinical testing in which a cooled air system was applied to patients. LRS plans to initially conduct tests using a physical model of the body to optimize the design of the THD. It will then conduct animal studies (50 Kg swine) to further optimize the system, to evaluate the repeatability of the cooling which can be delivered, to compare the performance of the device to other cooling methods (such as standard cooling blankets), and to evaluate the ability of the THD to operate simultaneously with the delivery of CPR. During cooling experiments, temperatures will be monitored in the animal's pulmonary artery, auditory canal, and skin. In addition, EKG, blood pressures, and other key physiologic parameters will be monitored. The tests described in this proposal will be followed in the future by other tests (in both animals and humans) investigating the ability of the THD, in combination with other measures such as CPR, to improve neurologically intact survival following cardiac arrest. Long term, LRS believes that the THD has the potential to significantly increase the chances of neurologically intact survival following cardiac arrest. It also plans to evaluate the effectiveness of the THD in the treatment of other conditions, such as stroke.